This application is a continuation in part of the disclosure filed on Aug. 23, 1982, by the present inventor, which disclosure bears Ser. No. 410,524. As set forth in that disclosure and in particular as found at FIG. 8 thereof, a multi-piece construction bullet is described. This disclosure sets forth a multi-piece construction bullet having certain improvements and advances which are to be noted hereinbelow. The bullet construction of this disclosure should be particularly compared with that found in the patent of Urbanosky. U.S. Pat. No. 3,329,217 sets forth a straight sided bullet which disclosure primarily focuses on a slidable inner sleeve for gathering a particulate formation such as an unconsolidated sand. Urbanosky also shows in U.S. Pat. No. 3,220,493 a straight sided cylindrical bullet construction. This bullet incorporates a snap ring 26 which supports a release ring 25 on a forward shoulder. The ring is greater in diameter than the diameter of the bullet body. Austrian Pat. No. 204,981 shows a single piece construction bullet body having no release ring. It is of single piece construction. Austrian Pat. No. 268,170 discloses a bullet body of straight cylindrical sidewall construction.
These references do not disclose a formation sampling bullet which is constructed with telescoped components incorporating a relatively small sacrificial release ring means. In this construction, the release ring is secured next to an encircling groove on the outer face at the nose portion. When the bullet enters a formation to take a sample, the tapered outer face at the nose portion is jammed into the formation by the energy pushing the bullet, and the bullet is able to penetrate to a suitable depth. During penetration, the bullet body momentum forces the sloping or tapered outer face against the formation whereupon the release ring means serves as a brake to limit unnecessary bullet penetration. The release ring slides and possibly distorts during sliding movement. The outside ring diameter is intended to free the bullet for retrievability. That is, the sacrificial release ring is interposed between the bullet body and the formation to thereby lessen the grip of the formation. The notches in the inside diameter of the release ring are intended to vent mud suction. The bullet body is retrieved by pulling the bullet body with a retrieval cable or the like. This retrieval cable breaks the bullet body free and enables the user to retrieve the bullet body. The release ring is normally left in the formation, and the body can thereafter be used again and again.
The multi-piece construction bullet of this disclosure particularly enables substitution of nose portions. They can be changed dependent upon the nature of the formation encountered. Such changes might incorporate a longer or shorter nose portion; also, the radius of curvature at the nose portion can be changed. The angle of taper of the nose portion can likewise be varied. The dimensions of the internal longitudinal bore can also be changed. It is relatively less expensive to change only the nose portion as opposed to discarding the entire bullet body. The nose portion, with sample intact, can be separated from the carrier to submit the uncontaminated, unbroken sample intact for laboratory testing.
With the foregoing in view, the present disclosure presents a multi-piece construction sample collecting bullet body formed of three pieces in the preferred embodiment. There is a first or forward portion, which is known as the nose portion. It joins to a carrier portion and receives a bottom cap therein. They are secured together by connection at internal mating shoulder surfaces, and are fastened together as an assembly enabling a sample to be received in the longitudinal bore. Because of the exterior-interior angle relationships, the sample can be retrieved quite readily upon retrieval of the bullet. The bullet incorporates a sacrificial release ring on the outer face of the nose portion. The release ring is constructed with relieving flow paths for vents to enable drilling mud and debris to slide past the release ring.
This application is a continuation-in-part of application Ser. No. 410,524 filed Aug. 23, 1982 by the same inventor.